The present invention relates to a moistener nozzle control system. More particularly, the present invention relates to a method for positioning a nozzle in a moistener of a mailing machine.
Modern mail-handling machines which seal envelopes typically include a moistener for moistening the envelope flap. After moistening, the flap is then sealed before it is passed on to a scale and postage meter. Mail-handling machines employ a wide variety of moisteners.
Bach et al. U.S. Pat. No. 2,944,511 shows an envelope flap moistener which includes a brush that is brought into contact with the flap. A disadvantage of this particular type of moistener is that it requires physical contact between the brush and the flap to be moistened. Furthermore, it is "non-selective" in that it moistens the entire flap without distinguishing between the gummed and non-gummed regions of the flap.
Fassman et al. U.S. Pat. No. 4,926,787 shows another non-selective and contact-requiring envelope flap moistener. Moistening is provided by a pad made of a fluid wicking material.
Lupkas U.S. Pat. No. 3,911,862 shows a non-contact envelope flap moistener. It includes a jet or nozzle which sprays a moistening fluid upon the gum of the flap. The spray is applied as the envelope moves past the nozzle. A photocell sensor controls the application of the spray by sensing the passage of the envelope and/or its flap. The spray is applied in tiered segmented fashion to the flap in order to moisten substantially the entire gummed surface of the flap. The segmented spray is achieved either by (1) moving the nozzle, or (2) providing a selective spraying using a pair of closely spaced nozzles.
O'Dea et al. U.S. Pat. No. 5,007,371 also shows a non-contact envelope flap moistener employing a nozzle. This moistening arrangement includes a sensor arrangement for sensing the width of an envelope flap and a control arrangement for controlling the position of the moistener.
In general, moisteners which employ a motor-controlled nozzle include a device for detecting the presence of an envelope flap. The presence-detecting device is used to turn a motor on and off in order to move and position the nozzle so that it will selectively spray only on the gummed regions of the envelope flap. In modern mail-handling machines, which process envelopes moving at high speeds, the motor-controlled nozzle must be able to quickly respond to the presence-detecting device to assure proper moistening of a fast-moving envelope flap.
For a given envelope speed through a mailing machine, the response time of the motor-controlled nozzle limits the size of the envelope flap under which a moistener can be used. If the response time is too slow, the nozzle cannot be re-positioned quickly enough in order to accurately follow the gummed region of the envelope flap. Under these conditions, the nozzle would not be able to get to the gum line of large envelope flaps until well past the beginning of the envelope. This can result in significant parts of large envelope flaps that remain unsealed.
The difficulty in sealing large envelope flaps could be minimized, to some extent, by optimizing the moistener nozzle control system so that it can perform better with larger envelope flaps. However, it is desirable that a moistener nozzle control system be able to handle a mixed succession of a random mix of both large and small envelope flaps without the need for manual intervention or sorting of envelopes. If a moistener nozzle control system is optimized solely for large envelope flaps this might negatively impact the sealing of small envelope flaps.
When a motor-controlled nozzle is required to move quickly for re-positioning, the motor must normally be controlled under high-torque conditions. Operating a nozzle motor continuously, especially under high-torque conditions, may have disadvantages. Because the average motor temperature is directly related to the amount of time that the motor is operated, the longer that a motor is operated, the higher its temperature will be. In addition, operation under high-torque conditions further increases the temperature of the motor. Reducing average motor temperature results in a savings in motor cost and an increase in motor lifetime. Furthermore, the amount of time that a nozzle motor is operated determines the motor power supply requirements. Reducing the amount of time that a motor is operated, especially under high-torque conditions, reduces power consumption and therefore power supply cost.
In view of the above, it would be desirable to be able to provide a moistener nozzle control system for a moistener that is contactless, selective, and yet is capable of operating in a high-speed environment.
It would also be desirable to be able to provide such a moistener nozzle control system which has a fast enough response time that envelopes with large flaps can be properly moistened.
It would further be desirable to be able to provide a moistener nozzle control system that can handle a mixed succession of a random mix of both large and small envelope flaps without the need for manual intervention or sorting of envelopes.
It would still further be desirable to be able to provide a moistener nozzle control system which does not require a nozzle motor to be operated as frequently, especially under high-torque conditions, so that the average temperature and power consumption of the motor can be reduced.